Update
- Edges are now stored in a map with tuple keys (from node, to node)
- New key hash function added for tuples
- Memory leak detected! Blank please fix!
- Also, odd number of edges when summarizing edges_in and edges_out over
all nodes. Should be an even number! Blank please fix!
Merge branch 'master' of https://github.com/bgrimstad/graph

Conflicts:
	graph.h